Consumption of CH<sub>3</sub>Cl, CH<sub>3</sub>Br, and CH<sub>3</sub>I and emission of CHCl<sub>3</sub>, CHBr<sub>3</sub>, and CH<sub>2</sub>Br<sub>2</sub> from the forefield of a retreating Arctic glacier
<p>The Arctic is one of the most rapidly warming regions of the Earth, with predicted temperature increases of 5–7 <span class="inline-formula"><sup>∘</sup></span>C and the accompanying extensive retreat of Arctic glacial systems by 2100. Retreating...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2020-06-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/20/7243/2020/acp-20-7243-2020.pdf |
| _version_ | 1811340647826718720 |
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| author | M. L. Macdonald J. L. Wadham D. Young C. R. Lunder O. Hermansen G. Lamarche-Gagnon S. O'Doherty |
| author_facet | M. L. Macdonald J. L. Wadham D. Young C. R. Lunder O. Hermansen G. Lamarche-Gagnon S. O'Doherty |
| author_sort | M. L. Macdonald |
| collection | DOAJ |
| description | <p>The Arctic is one of the most rapidly warming regions of the Earth, with
predicted temperature increases of 5–7 <span class="inline-formula"><sup>∘</sup></span>C and the accompanying
extensive retreat of Arctic glacial systems by 2100. Retreating glaciers
will reveal new land surfaces for microbial colonisation, ultimately
succeeding to tundra over decades to centuries. An unexplored dimension to
these changes is the impact upon the emission and consumption of halogenated
organic compounds (halocarbons). Halocarbons are involved in several
important atmospheric processes, including ozone destruction, and despite
considerable research, uncertainties remain in the natural cycles of some of
these compounds. Using flux chambers, we measured halocarbon fluxes across
the glacier forefield (the area between the present-day position of a
glacier's ice-front and that at the last glacial maximum) of a high-Arctic
glacier in Svalbard, spanning recently exposed sediments (<span class="inline-formula"><10</span> years) to approximately 1950-year-old tundra. Forefield land surfaces were
found to consume methyl chloride (<span class="inline-formula">CH<sub>3</sub>Cl</span>) and methyl bromide
(<span class="inline-formula">CH<sub>3</sub>Br</span>), with both consumption and emission of methyl iodide
(<span class="inline-formula">CH<sub>3</sub>I</span>) observed. Bromoform (<span class="inline-formula">CHBr<sub>3</sub></span>) and dibromomethane
(<span class="inline-formula">CH<sub>2</sub>Br<sub>2</sub></span>) have rarely been measured from terrestrial sources but
were here found to be emitted across the forefield. Novel measurements
conducted on terrestrial cyanobacterial mats covering relatively young
surfaces showed similar measured fluxes to the oldest, vegetated tundra
sites for <span class="inline-formula">CH<sub>3</sub>Cl</span>, <span class="inline-formula">CH<sub>3</sub>Br</span>, and <span class="inline-formula">CH<sub>3</sub>I</span> (which were consumed) and for
<span class="inline-formula">CHCl<sub>3</sub></span> and <span class="inline-formula">CHBr<sub>3</sub></span> (which were emitted). Consumption rates of
<span class="inline-formula">CH<sub>3</sub>Cl</span> and <span class="inline-formula">CH<sub>3</sub>Br</span> and emission rates of <span class="inline-formula">CHCl<sub>3</sub></span> from tundra and
cyanobacterial mat sites were within the ranges reported from older and more
established Arctic tundra elsewhere. Rough calculations showed total
emissions and consumptions of these gases across the Arctic were small
relative to other sources and sinks due to the small surface area
represented by glacier forefields. We have demonstrated that glacier
forefields can consume and emit halocarbons despite their young age and low
soil development, particularly when cyanobacterial mats are present.</p> |
| first_indexed | 2024-04-13T18:45:05Z |
| format | Article |
| id | doaj.art-23789b7c9ca44e30ab9b0a234e99b1bd |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-04-13T18:45:05Z |
| publishDate | 2020-06-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-23789b7c9ca44e30ab9b0a234e99b1bd2022-12-22T02:34:36ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242020-06-01207243725810.5194/acp-20-7243-2020Consumption of CH<sub>3</sub>Cl, CH<sub>3</sub>Br, and CH<sub>3</sub>I and emission of CHCl<sub>3</sub>, CHBr<sub>3</sub>, and CH<sub>2</sub>Br<sub>2</sub> from the forefield of a retreating Arctic glacierM. L. Macdonald0J. L. Wadham1D. Young2C. R. Lunder3O. Hermansen4G. Lamarche-Gagnon5S. O'Doherty6School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, UKSchool of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, UKSchool of Chemistry, University of Bristol, Bristol, BS8 1TS, UKNorwegian Institute for Air Research (NILU), Kjeller, 2027, NorwayNorwegian Institute for Air Research (NILU), Kjeller, 2027, NorwaySchool of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, UKSchool of Chemistry, University of Bristol, Bristol, BS8 1TS, UK<p>The Arctic is one of the most rapidly warming regions of the Earth, with predicted temperature increases of 5–7 <span class="inline-formula"><sup>∘</sup></span>C and the accompanying extensive retreat of Arctic glacial systems by 2100. Retreating glaciers will reveal new land surfaces for microbial colonisation, ultimately succeeding to tundra over decades to centuries. An unexplored dimension to these changes is the impact upon the emission and consumption of halogenated organic compounds (halocarbons). Halocarbons are involved in several important atmospheric processes, including ozone destruction, and despite considerable research, uncertainties remain in the natural cycles of some of these compounds. Using flux chambers, we measured halocarbon fluxes across the glacier forefield (the area between the present-day position of a glacier's ice-front and that at the last glacial maximum) of a high-Arctic glacier in Svalbard, spanning recently exposed sediments (<span class="inline-formula"><10</span> years) to approximately 1950-year-old tundra. Forefield land surfaces were found to consume methyl chloride (<span class="inline-formula">CH<sub>3</sub>Cl</span>) and methyl bromide (<span class="inline-formula">CH<sub>3</sub>Br</span>), with both consumption and emission of methyl iodide (<span class="inline-formula">CH<sub>3</sub>I</span>) observed. Bromoform (<span class="inline-formula">CHBr<sub>3</sub></span>) and dibromomethane (<span class="inline-formula">CH<sub>2</sub>Br<sub>2</sub></span>) have rarely been measured from terrestrial sources but were here found to be emitted across the forefield. Novel measurements conducted on terrestrial cyanobacterial mats covering relatively young surfaces showed similar measured fluxes to the oldest, vegetated tundra sites for <span class="inline-formula">CH<sub>3</sub>Cl</span>, <span class="inline-formula">CH<sub>3</sub>Br</span>, and <span class="inline-formula">CH<sub>3</sub>I</span> (which were consumed) and for <span class="inline-formula">CHCl<sub>3</sub></span> and <span class="inline-formula">CHBr<sub>3</sub></span> (which were emitted). Consumption rates of <span class="inline-formula">CH<sub>3</sub>Cl</span> and <span class="inline-formula">CH<sub>3</sub>Br</span> and emission rates of <span class="inline-formula">CHCl<sub>3</sub></span> from tundra and cyanobacterial mat sites were within the ranges reported from older and more established Arctic tundra elsewhere. Rough calculations showed total emissions and consumptions of these gases across the Arctic were small relative to other sources and sinks due to the small surface area represented by glacier forefields. We have demonstrated that glacier forefields can consume and emit halocarbons despite their young age and low soil development, particularly when cyanobacterial mats are present.</p>https://www.atmos-chem-phys.net/20/7243/2020/acp-20-7243-2020.pdf |
| spellingShingle | M. L. Macdonald J. L. Wadham D. Young C. R. Lunder O. Hermansen G. Lamarche-Gagnon S. O'Doherty Consumption of CH<sub>3</sub>Cl, CH<sub>3</sub>Br, and CH<sub>3</sub>I and emission of CHCl<sub>3</sub>, CHBr<sub>3</sub>, and CH<sub>2</sub>Br<sub>2</sub> from the forefield of a retreating Arctic glacier Atmospheric Chemistry and Physics |
| title | Consumption of CH<sub>3</sub>Cl, CH<sub>3</sub>Br, and CH<sub>3</sub>I and emission of CHCl<sub>3</sub>, CHBr<sub>3</sub>, and CH<sub>2</sub>Br<sub>2</sub> from the forefield of a retreating Arctic glacier |
| title_full | Consumption of CH<sub>3</sub>Cl, CH<sub>3</sub>Br, and CH<sub>3</sub>I and emission of CHCl<sub>3</sub>, CHBr<sub>3</sub>, and CH<sub>2</sub>Br<sub>2</sub> from the forefield of a retreating Arctic glacier |
| title_fullStr | Consumption of CH<sub>3</sub>Cl, CH<sub>3</sub>Br, and CH<sub>3</sub>I and emission of CHCl<sub>3</sub>, CHBr<sub>3</sub>, and CH<sub>2</sub>Br<sub>2</sub> from the forefield of a retreating Arctic glacier |
| title_full_unstemmed | Consumption of CH<sub>3</sub>Cl, CH<sub>3</sub>Br, and CH<sub>3</sub>I and emission of CHCl<sub>3</sub>, CHBr<sub>3</sub>, and CH<sub>2</sub>Br<sub>2</sub> from the forefield of a retreating Arctic glacier |
| title_short | Consumption of CH<sub>3</sub>Cl, CH<sub>3</sub>Br, and CH<sub>3</sub>I and emission of CHCl<sub>3</sub>, CHBr<sub>3</sub>, and CH<sub>2</sub>Br<sub>2</sub> from the forefield of a retreating Arctic glacier |
| title_sort | consumption of ch sub 3 sub cl ch sub 3 sub br and ch sub 3 sub i and emission of chcl sub 3 sub chbr sub 3 sub and ch sub 2 sub br sub 2 sub from the forefield of a retreating arctic glacier |
| url | https://www.atmos-chem-phys.net/20/7243/2020/acp-20-7243-2020.pdf |
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